NEW YORK/BENGALURU (Reuters) - Transportation stocks went sharply in reverse on Friday with the economic bellwether Dow Jones Transport average index falling more than 2.6% in its steepest daily loss since December 18 and its third consecutive decline, as investors reacted to weak economic readings and worried about tariffs.

UnitedHealth Group tumbled more than 8.6% in premarket after the Wall Street Journal reported that the U.S. Department of Justice is investigating the health care giant's Medicare billing practices. The report published Friday referred to the DOJ's action as a “civil fraud investigation.”